1. Field of the Invention
This invention generally relates to a diaphragm spring assembly for a clutch cover assembly. More specifically, the present invention relates to a diaphragm spring assembly for a clutch cover assembly which use two diaphragm springs one on top of the other to increase the capacity of torque transmission.
2. Background Information
A multi-plate clutch is often used in such vehicles as racing cars. Multi-plate clutches generally comprise a flywheel on the engine side, a clutch cover assembly disposed axially apart from the flywheel, and a plurality of input and output members (for example, drive and driven plates) disposed between the flywheel and the pressure plate of the clutch cover assembly. The term "multi-plate clutch" as used herein means a clutch in which more than two output portions are disposed and more than three friction connecting faces are formed by the input member and the output member.
The flywheel and the clutch cover in the multi-plate clutch are typically coupled together by, for example, a cylindrical member. The cylindrical member is disposed on the outer circumferential side of the drive and driven plates. The cylindrical member has a plurality of teeth disposed circumferentially next to one another on the inner circumferential face. The teeth of the cylindrical member extend in an axial direction on the inner circumferential face and engage outer circumferential teeth of the drive plate. This engagement makes the drive plate axially movable and circumferentially unmovable against the cylindrical member. In other words, a torque is transmitted from the flywheel to the drive plate via the cylindrical member.
Some multi-plate clutches have a boss not only used to couple the flywheel and the clutch cover together, but also used to drive a drive plate. The boss is often a column like member extending in an axial direction, with radially extending spaces being formed in between circumferentially adjacent column like members. A connecting portion is formed on the outer circumference of the drive plate. The connecting portion is inserted in the spaces described above and engages the boss such that it is axially movable and circumferentially non-movable.
A conventional multi-plate clutch described above requires large pressing load of a diaphragm spring to increase the torque transmission capacity without increasing the size of the clutch. Some multi-plate clutches use two diaphragm springs, one next to the other, for that purpose. The two diaphragm springs have identical annular elastic portions and plurality of lever portions, each of which is disposed axially next to each other.
Therefore, when a member such as a release device needs to be installed at the tip of the lever portions, the release device is fixed to the inner periphery of the two diaphragm springs. This release device has to have a different structure from the release device that is fixed to the inner periphery of one diaphragm spring. As a result, several different kinds of release devices have to be manufactured, which increases the cost.
In view of the above, there exists a need for a diaphragm spring assembly and a clutch cover assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.